start loading the background images when we resolve style on an object that
needs them instead of when we scroll down and see it for the first time. Bug
57607, r=pavlov, sr=dbaron
Use the property list in the tables for nsRuleNode::CheckSpecifiedProperties.
To reduce heap usage, redesign the storage of properties and values in nsCSSDeclaration to allocate all property-value pairs in a declaration block in a single allocation, and use temporary structures (like the old permanent structures) during parsing and modification. Replace per-property switch statements in nsCSSDeclaration with table-based code to reduce code size.
b=125246 r+sr=bzbarsky
